FatCat

Hi guys, I just have a quick question for everyone. I am flying a Hobbico Superstar with a TT .46 turning a Master Airscrew 11x6. For the winter months I am planning on installing some skis, but want to know what choice I should make for my propeller. I was thinking about dropping down to at least a 10 inch to allow for snow clearance. What is a good recommendation that will still give me clearance and enough thrust to overcome the drag of those big ski's hanging down? I appreciate the help!!

rc-sport

My Feedback: (12)

I don't change the prop but I make my own skies. I make the mounting point on the ski the same height as the hub on the wheel.

FatCat

Thanks rc, but it isn't the ski height I am concerned about...it is the prop hitting the snow when the skis are an inch or so under the powder. If I was flying on hard packed snow, then it wouldn't be an issue.

gus

My recommendation ... go out and see if what you have is OK. If were you though, I would spend a few dollars, and get APC 11x5, APC11x4, and maybe an APC 10x5. Then try each one and see what works... I always recommend APC because of personal preference, and experience, but there is no better alternative than trying things yourself.

The smaller pitches will give you slightly more RPM, and way more thrust that will be better at overcomming any resistance on the skiis. It also gives you a better braking mechanism when landing, but it will reduce your top-speed. If ou are a speed daemon, then you will feel cheated with a smaller pitch.

On the flip side, I don't have snow experience (yet), but what I have recommended to you is exactly what I am going to do when santa brings some skiis for my plane!

In my ski-on-a-plane research, I have heard it said that when the snow is really powdery, then the best thing is to fly off floats!

gus

Rick Lindsey

I'm an utter novice, so keep your salt shaker handy, but...

It seems to me that you'd want as much thrust as possible to overcome the ski drag. Would it be possible to keep your 11x6 prop and use a taller landing gear for your skis? I'm not sure how easy it'd be to trade out your landing gear rather than just bolt ski's on where your wheels used to be, but it might be worth the effort to stick some taller landing gear on to make up the difference in ground clearance rather than using a smaller diameter prop...

Sorry I can't answer your real question (which prop to use) but maybe there's an alternate solution to the problem (prop hitting the snow)

CafeenMan

I like low-pitch props on trainers because they give finer throttle control at the speeds they are designed to fly.

swooper

I've always used whatever prop is on for the summer. If the tips brush a little snow, what difference? I've seen my planes throwing a bit of "contrail" on takeoff but haven't heard engine missing or anything, it didn't seem to matter.

As for thrust requirements, don't think you need any more. From what I've seen, the skis are mounted with some positive incidence. I think they generate some lift along with some drag. My planes fly just as well with skis, but slower. Some of this has to be the increased air density. Also, taking off and landing from/onto snow is easy unless it's just too deep.

Your engine should be producing more power for the same reason, more density. So just try the usual setup, I think it will work fine.

phread59

I also have never flown from snow (BTW smow is a four letter word!!!!). But I would say keep the diameter. Diameter givs you power. You may need it from the snow's drag on the skis. I would get an 11-5 and maybe a few APC props as well and try different props while taxiing. I wish you well.

Mark Shuman